Bug fixes & improvements on Flutter plugin example app (#359)

* Remove unneeded resource files from iOS Project

* Remove breez_liquid_sdk.h
* Remove outdated method to enforce bundling on AppDelegate

* Add NSCameraUsageDescription to be able to scan QR codes on example app

* Do not show "No Balance" text when balance is 0

* Wait for reconnect attempt on startup

* Add a cancel button to mobile scanner

* Bound size of QR image view

* Reverse the payment list

packages/flutter/example/lib/routes/home/widgets/qr_scan/barcode_scanner_simple.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:flutter/material.dart';
 import 'package:flutter_breez_liquid_example/routes/home/widgets/qr_scan/scan_overlay.dart';
+import 'package:flutter_breez_liquid_example/routes/home/widgets/qr_scan/scanner_button_widgets.dart';
 import 'package:flutter_breez_liquid_example/routes/home/widgets/qr_scan/scanner_error_widget.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
 
@@ -82,6 +83,7 @@ class _BarcodeScannerState extends State<BarcodeScanner> with WidgetsBindingObse
     var scanWindowDimension = MediaQuery.of(context).size.width - 72;
     return Scaffold(
       body: Stack(
+        fit: StackFit.expand,
         children: [
           MobileScanner(
             scanWindow: Rect.fromCenter(
@@ -98,6 +100,18 @@ class _BarcodeScannerState extends State<BarcodeScanner> with WidgetsBindingObse
             },
             fit: BoxFit.cover,
           ),
+          Align(
+            alignment: Alignment.bottomCenter,
+            child: Row(
+              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+              children: [
+                Padding(
+                  padding: const EdgeInsets.only(bottom: 40),
+                  child: CancelScanButton(controller: controller),
+                )
+              ],
+            ),
+          ),
         ],
       ),
     );

packages/flutter/example/lib/routes/home/widgets/qr_scan/scanner_button_widgets.dart

@@ -128,3 +128,40 @@ class ToggleFlashlightButton extends StatelessWidget {
     );
   }
 }
+
+class CancelScanButton extends StatelessWidget {
+  const CancelScanButton({required this.controller, super.key});
+
+  final MobileScannerController controller;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      decoration: BoxDecoration(
+        borderRadius: const BorderRadius.all(
+          Radius.circular(12.0),
+        ),
+        border: Border.all(
+          color: Colors.white.withOpacity(0.8),
+        ),
+      ),
+      child: TextButton(
+        style: TextButton.styleFrom(
+          padding: const EdgeInsets.only(
+            right: 35,
+            left: 35,
+          ),
+        ),
+        onPressed: () async {
+          controller.stop().then((_) => Navigator.of(context).pop());
+        },
+        child: const Text(
+          "CANCEL",
+          style: TextStyle(
+            color: Colors.white,
+          ),
+        ),
+      ),
+    );
+  }
+}